Gravity valve



June 30, 1970 GRAVITY VALVE Z Sheets-Sheet 1 Filed June 10, 1968 5% V M Ma v N a N W 1km 0 T 6 y w J w V \k June 30, 1970 LEUTWYLER ETAL GRAVITY VALVE 2 Sheets-Sheet :3

Filed June 10, 1968 INVEN Toes mi 2 2% Emma L; T. w EM illlfllL' United States Patent 3,518,027 GRAVITY VALVE Kurt Leutwyler, Houston, Tex., and John C. Falanga, .lr., Metairie, La., assignors to Baker Oil Tools, Inc., City of Commerce, Calif., a corporation of California Filed June 10, 1968, Ser. No. 735,788 Int. Cl. F04f 1/00, 1/08 U.S. Cl. 417-65 19 Claims ABSTRACT OF THE DISCLOSURE In the production of certain gas wells or wells having a high gas/oil ratio, it sometimes occurs that fluid, such as water or oil, may accumulate in the well, forming a hydrostatic column which resists flow of gas into the well and to the surface.

Heretofore, it has been proposed that such accumulation of liquid can be prevented by intermittently causing the flow of the liquid to the top of the well through a string of tubing, under the control of a gas lift valve and a differential pressure responsive valve mechanism operable when the liquid level rises beyond a predetermined level, to allow gas to enter the gas lift valve and operate the same to lift a slug of liquid through the tubing.

However, it is desirable that the valve mechanism, including the differential pressure responsive intermitter or valve, as well as the gas lift valve, be capable of being run into the tubing and recovered therefrom on a wireline. Hence, the assemblies must be of small diameter capable of freely moving through the tubing. The provision of differential fluid level or pressure responsive apparatus for effecting operation of the valve means within a small body is thus a problem which is difllcult to solve.

The present invention provides a fluid level responsive valve means adapted to be employed in such apparatus and operable to produce a comparatively large valve operating force in response to relatively small differential fluid columns or pressure acting on the valve operating means.

More specifically, the invention provides a differential pressure responsive gravity valve means, which may be combined with a gas lift valve and run into a well on a wireline and anchored at the desired location in the tubing string, whereby, when the liquid in the well, such as water and/or oil, rises beyond a predetermined level, the gravity valve will open to allow the gas in the well to cause movement of the liquid into the tubing string until the liquid level has been reduced to a predetermined level, whereupon the valve will close, the gravity valve having operating means so constructed as to produce a large operating force in response to a comparatively small change in liquid level, thereby assuring actuation of the valve, as well as allowing adjustment thereof over a substantial range of differential pressure response.

This invention possesses many other advantages, and has other purposes which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It

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will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIG. 1 is a diagrammatic view, partially sectional and partially in elevation, of a well producing system including the present invention;

FIGS. 2a and 2b together constitute a longitudinal sectional view of the gravity valve of FIG. 1 disposed in a well and in closed condition;

FIG. 3 is a fragmentary view, corresponding to FIGS. 2a and 211, but showing the valve open;

FIG. 4 is a transverse section taken on the line 4-4 of FIG. 3;

FIG. 5 is a transverse section taken on the line 5-5 of FIG. 2b; and

FIG. 6 is a fragmentary view showing the valve actuator means in elevation, as seen on the line 6-6 of FIG. 3.

The invention is typically applicable to a gas well W, which is also producing some water or oil. It is desired to hold the water or oil level in the well bore to a low value, to reduce the back pressure against the gas producing formation F so as to offer minimum resistance to the flow of gas into the well bore. As disclosed diagrammatically in FIG. 1, a well casing C is disposed in a well bore, which has perforations 10 opposite the gas producing formation or zone F. A tubing string T extends into the well casing from the top of the well bore, through which it is desired to produce or lift the water, or other liquid, in the well casing to the surface, the liquid and some gas passing through a master valve 11 at the top of the well and then through a branch line 12 to a suitable tank or pit (not shown), the flow of fluid through the branch line being controlled by a suitable valve 13. The gas passes upwardly through the tubing-casing annulus A to the top of the well bore and then through a gas line 14 for distribution to a desired location. An equalizing line 15 extends between the tubing string T above the master valve 11 and the gas line 14, which is controlled by a valve 16 that will normally be closed, this equalizing line being used for equalizing the pressure within the tubing string and easing string, when desired.

The liquid in the casing string C is maintained at a low level, which preferably is below the elevation of the casing perforations 10, the liquid being produced through the tubing string T. The passage of liquid into the tubing string is controlled by a gravity valve B disposed within the lower end of the tubing string T, as will be hereinafter described, the liquid passing upwardly through a differential gas lift valve D and through a lock assembly E into the tubing string T above the latter. The lock assembly, differential gas lift valve, and gravity valve can be lowered as a unit on a wireline (not shown) from the top of the well bore through the tubing string to a desired location in the lower portion of the tubing string, as determined by engagement of the body 17 of the lock assembly with a companion shoulder 18 in a seating nipple 19 forming part of the tubing string, the lock assembly including latches 20 that can expand outwardly into a companion circumferential locking groove 21 in the seating nipple, to prevent inadvertent upward movement of the lock assembly E, gas lift valve D, and gravity valve B within the tubing string, after the apparatus has been landed therewithin. The lock assembly carries a suitable side seal 22 sealing against the inner wall 23 of the seating nipple to prevent any fluids, either gas or liquid, from passing between the lock assembly and the seating nipple and into the tubing string. The lock assembly has a suitable fishing head 24 at its upper portion for lowering the equipment, which ineludes the lock assembly, differential gas lift valve, and gravity valve, in the well casing on a wirelinefnot shown) through the tubing string, and for releasing the lock assembly E from the seating nipple 19 through retraction of its latches 20 and for elevating the combination of equipment through the tubing string to the top of the well bore. The lock assembly, per se, forms no part of the present invention and can be of any known type. As an example, it may be of the type illustrated in US. Letters Pat. No. 2,885,007. The gas lift valve may be constructed in accordance with the disclosure of the US. patent application of David V. Chenoweth, Ser. No. 609,028, filed Jan. 13, 1967, for Subsurface Well Intermitter, now Pat. No. 3,433,174.

The tubing string T below the seating nipple 19 has a downwardly extended section 19a provided with perforations to permit the gas under pressure in the well casing to enter the interior of the tubing string through the gas lift valve D.

Referring to FIGS. 2a and 2b, the gravity valve B of the invention will be seen to comprise an elongated tubular body including a top plug or transverse wall 31 having a neck 32 threadedly connected to a coupling 33 which is, in turn, threaded to the lower end of the tubular body 34 of the gas lift valve D previously referred to. Beneath the top plug 31, the valve body 30 includes a cylindrical section 35 which fits upon a stem section 36 of the plug 31 and is suitably secured thereto, as by a weld 37. At the lower end of the valve body section 35, it is threadedly connected, as at 38, to a plug or transverse Wall 39, a

suitable seal ring 40 being provided between the outer wall 41 of the plug 39 and a cylindrical downward extension 42 of the body section 35.

The body 30 further includes a lower tubular body section 43 which depends from the plug 39. The plug 39 has a flange 44 and the body section 43 has a connector sleeve 45 provided with an inwardly extended flange 45a at its upper end which hangs the sleeve on the plug flange 44 at its lower end, the connector sleeve 45 being threaded, as at 46, within the upper end of the lower body section 43. At the lower end of the body section 43 is a spring housing 47 connected to the body section 43 by a threaded joint at 48.

Inlet ports 50 are provided in the coupling sleeve 45 for the admission of liquid, such as water and/ or oil, from the well casing C, so that such liquid may pass through the gravity valve B and gas lift valve D into the well tubing T, as will be hereinafter described. Extending through the plug 39 is a pasage 51 communicating with the ports 50 through a suitable valve seat member 52 having a central port 53 circumscribed by a seat 54, which seat is engageable by the head of the valve stem 55, to shut off communication between the passage 51 and the well casing. In order to establish communication between this passage 51 and the gas lift valve D thereabove, a tube 56 is joined to the plug 39, as by a weld 57, and extends upwardly through the top plug 31, opening into the lower end of the gas lift valve body 34, the tube 56 being also welded at '58 to the plug 31.

The above-mentioned valve stem is part of the valve means, generally denoted at 60, the stem 55 being threadedly adjustable on the upper end of an actuator member or rod 61, as at 62. This rod 61 extends downwardly through the body section 43 and through a disc or seat 63 which is disposed on an internal shoulder 64 in the spring housing 47. At its lower extremity, the rod 61 supports a spring seat 65 threadedly mounted thereon and adapted to be locked in place by a washer 66 and lock nut 67. A coiled or helical compression spring 68 is compressed between the seat 63 and 65, providing means for normally biasing the rod 61 downwardly to move the stem 55 of the valve means to a position spaced from the seat 54 so that the valve is open. The adjustable spring seat provides for adjusting the valve actuating force of the spring 68.

Means are provided responsive to the level of water and/ or oil in the casing for moving the valve means to a closed position when the liquid level is at the desired or predetermined low level, and for allowing the valve means to move to the open position when the liquid level rises to a predetermined level. These means are shown in FIGS. 2b, 3 and 6 as including an elongated bladder of elastomeric material, denoted at 70, formed in a helical coil, and disposed between a helical rib 71 on the rod 61 and a stationary helical support 72 within the body section 43.

The helical support 72 seats at its lower end 73 on the disc or seat 63 referred to above and spirals upwardly within the body 43, being confined therein by a retainer ring 74 engaging its upper end 73a and which seats on a shoulder 75 and is retained by the lower end face 76 of the coupling sleeve 45. The helical rib '71 is integral with or otherwise is made a part of the valve rod 61. This rib 71 provides an underface 71a opposing the upper face 72a of the helical support 73, so as to provide a helical gap 78 in which the rubber or rubber-like helical bladder 70 is disposed, the bladder being in engagement with the opposing faces 71a and 72a and being confined laterally between the rod 61 and the body 43.

At its lower end, the bladder 70 is closed and fastened beneath the support 73, as by a fastener 80, and at its upper end, the bladder is suitably joined to a nipple 81, as at 82, the nipple being threaded into the plug 39 in communication with a passage 83 extending through the plug 39 into a chamber 84 defined within the body 43 between the plugs 31 and 39. Adjacent the upper region of the chamber 84, the body section 36 has ports 85. The chamber 84 below the ports 85 constitutes a reservoir for liquid, the reservoir communicating through the passage 83 in the plug 39 with the bladder 70 internally thereof. The exterior of the bladder 70 is exposed to fluid in the well casing entering through the ports 50 in the connector sleeve and also through the lower end of the spring housing 47.

It will now be apparent that the factors which determine the position of the valve stem 55, that is, whether the valve means is open or closed, are the valve opening force applied to the rod 61 by the spring 68, and the effective pressure differential acting on and in the bladder 70. Thus, if the column of fluid or effective hydrostatic pressure in the bladder 70 derived from the reservoir 84 sufficiently exceeds the effective hydrostatic pressure externally of the bladder 70 to overcome the effective force of the spring 68, then the bladder expands against the helical rib 71 to elevate the rod 61 and engage the valve stem 55 with the seat 54, the valve B thus being closed, as seen in FIGS. 2a and 212. However, if the effective force of the spring 68, plus the effective force derived from hydrostatic pressure externally of the bladder, exceeds the effective force derived from hydrostatic pressure internally of the bladder 70, then the spring can compress the bladder 70 and the valve means will be opened, as seen in 'FIG. 3.

From the foregoing, it will now be understood that a gravity valve B, as described above, is adapted to be combined with a gas lift valve D so as to function to periodically allow the passage of liquid, water and/or oil into the tubing to a predetermined level, after which the gas from the formation will cause operation of the gas lift valve D to intermittently lift the liquid in the tubing to the top of the well.

During the production of gas from the formation F, liquid in the well rises around the exterior of the gravity valve B and its bladder 70, the effective pressure on the outside of the bladder 70 increasing and offsetting to some extent the hydrostatic pressure of the liquid internally of the bladder, which is the height of the liquid column from the ports 85 to the lower end of the bladder, and which tends to inflate or expand the helical bladder 70 to hold the valve means 60 closed. When the liquid level externally of the bladder rises to the point that the pressure internally of the bladder is no longer capable of holding the valve means 60* closed against the opening force of the spring 68, the latter can shift the rod 61 downwardly to open the valve 60, allowing, as indicated by the arrows in FIG. 3, the flow of well liquid through the ports 50 and upwardly through the passage 51 in the plug 39, through tube 56 into the body 34 of the gas lift valve D. The gas lift valve D will function periodically to open 'when pressure from the formation F exceeds pressure of the column of fluid in the tubing T above the gas lift valve D, so that a slug of liquid will be produced through the tubing.

When the liquid level in the well is thus reduced to a level at which the effective pressure internally of the bladder 70 exceeds the force of the spring 68 and the effective pressure externally of the bladder 70, then the bladder will re-expand vertically to move the rod 61 upwardly and close the valve 60.

The differential hydrostatic head acting on the helical bladder 70 provides a relatively small resultant unit pressure within the bladder. The effective differential pressure is determined, as has been stated above, by the difference in liquid level acting on the interior of the bladder and the liquid level surrounding the gravity valve and acting on the exterior of the bladder. This difference in liquid level is not too great, since the distance between the ports 85 and the lower end of the bladder is relatively short, so that the unit differential pressure is relatively low. Despite its small value, the unit pressure is acting over a relatively large area of the helical bladder in view of its cross-sectional diameter and total length provided by its helical disposition within the helical gap 78. Thus, the unit pressure, by acting over a large area interiorly of the bladder, can develop a comparatively large total internal force on the bladder tending to expand it against the force of the spring 68 and the external liquid force. This enables the spring 68 to be provided with a stronger force and, therefore, allows a much stronger valve closing spring to be used.

We claim:

1. In valve apparatus for use in a tubular string disposed in a well bore for controlling the flow of fluid from the well bore into the tubular string: a valve body having a passage, a shiftable valve member movable axially in said body for closing said passage in a first position and opening said passage in a second position, and operating means responsive to the hydrostatic head of fluid in said well bore for shifting said shiftable valve member, said operating means including a stationary part, a movable part, and an elastic bladder between said parts responsive to the hydrostatic pressure of fluid in said bladder and the hydrostatic pressure of fluid in said well bore around said bladder for moving said movable part axially in one direction to shift said valve member to said first position, said hydrostatic pressure of fluid in said bladder being substantially constant and greater than the hydrostatic pressure of fluid in said well bore around said bladder, and means for normally biasing said movable part in the other direction to shift said valve member to said second position.

2. In valve apparatus for use in a tubular string disposed in a well bore for controlling the flow of fluid from the well bore into the tubular string: a valve body having a passage, a shiftable valve member movable axially in said body for closing said passage in a first position and opening said passage in a second position, and operating means responsive to the hydrostatic head of fluid in said well bore for shifting said shiftable valve member, said operating means including a stationary part, a movable part, and an elastic bladder between said parts responsive to the hydrostatic pressure of fluid in said bladder and in said well bore for moving said movable part axially in one direction, wherein said stationary part and said movable part have opposing surfaces forming a helical gap, and said bladder is in the form of a helical tube disposed in said gap.

3. Valve apparatus as defined in claim 2, wherein said tube being open at its upper end and having means closing its lower end, said body having a passage leading to said upper end of said tube for admitting the hydrostatic pressure of fluid in the well bore into said tube, the hydrostatic pressure of fluid in the well bore being applied to the outside of said tube in said gap below said lastmentioned passage.

4. In valve apparatus as defined in claim 1, said biaslngtmeans including a spring acting on said movable par 5. In valve apparatus for use in a tubular string disposed in a well bore for controlling the flow of fluid from the well bore into the tubular string: a valve body having a passage, a shiftable valve member movable axially in said body for closing said passage in a first position and opemng said passage in a second position, and operating means responsive to the hydrostatic head of fluid in said well bore for shifting said shiftable valve member, said operating means including a stationary part, a movable part, and an elastic bladder between said parts responsive to the hydrostatic pressure of fluid in said bladder and in said well bore for moving said movable part axially in one direction, wherein said movable part comprises an elongaterod having a helical rib extending therealong', said stationary part comprising a helical support in said body cooperating with said rib to form a helical gap, and said bladder comprises a tube extending helically in said p- 6. Valve apparatus as defined in claim 5, including a spring engaged with said rod for biasing said rod in the other direction.

7 Valve apparatus as defined in claim 5, including a spring engaged with said rod for biasing said rod in the other direction, said rod having adjustable means thereon for adjusting the effective force of said spring.

8. Yalve apparatus as defined in claim 1, wherein said body is provided with a valve seat circumscribing said passage, and said valve member has a head movable into and out of engagement with said seat.

9. Valve apparatus as defined in claim 1, wherein said body is provided with a valve seat circumscribing said passage, and said valve member has a head movable into and out of engagement with said seat, said movable part including a rod extending longitudinally in said body, said valve head being provided at one end of said rod, and said biasing means including spring means at the other end of said rod for biasing said rod to move said head away from said seat, said bladder being responsive to the pressure of fluid in said bladder to move said head toward said seat and responsive to pressure in said well to allow movement of said head away from said seat under the influence of said spring.

10. In valve apparatus for use in a tubular string disposed in a well bore for controlling the flow of fluid from the well bore into the tubular string: a valve body having a passage, a shiftable valve member movable axially in said body for closing said passage in a first position and opening said passage in a second position, and operating means responsive to the hydrostatic head of fluid in said well bore for shifting said shiftable valve member, said operating means including a stationary part, a movable part, and an elastic bladder between said parts responsive to the hydrostatic pressure of fluid in said bladder and in said well bore for moving said movable part axially in one direction, wherein said body is provided with a valve seat circu-mscr'ibing said passage, and said valve member has a head movable into and out of engagement with said seat, said movable part including a rod extending longitudinally in said body, said valve head being provided at one end of said rod, spring means at the other end of said rod for biasing said head away from said seat, said rod having a helical rib there- 7 along, said stationary part comprising a helical member cooperating with said rib to form a helical gap therewith, and said bladder comprising a tube extending helically in said gap and expansible and deformable in response to differential pressure of fluid in said tube and in said well.

11. In valve apparatus for use in a tubular string disposed in a well bore for controlling the flow of fluid from the well bore into the tubular string: an elongate tubular valve body having an upper wall, a reservoir chamber below said upper wall having a lateral port for communication with the well bore, a lower wall below said chamber, means defining a passage leading from above said upper wall to below said lower wall, valve means for opening and closing said passage operable responsive to the raising and lowering of the level of liquid in said well bore for opening and closing said valve means, said operating means including means forming a stationary helical support, a helical member cooperating with said support to form a helical gap therewith, and a bladder extending helically in said gap for moving said helical member in one direction when pressure in said bladder exceeds pressure outside of said bladder, and passage means leading from said reservoir chamber to said bladder.

12. In valve apparatus as defined in claim 11, resilient means acting on said helical member for biasing said helical member in the other direction.

13. Valve apparatus as defined in claim 11, wherein said valve means includes a stem on said helical member movable therewith to open and close said passage.

14. Valve apparatus as defined in claim 11, wherein said helical member includes an elongate rod having a helical rib thereon, and including a spring seat on said rod, and a spring engaged with said seat for biasing said helical member in the other direction.

15. Valve apparatus as defined in claim 11, wherein said helical member includes an elongate rod having a helical rib thereon, and including a spring seat on said rod, and a spring engaged with said seat for biasing said helical member in the other direction, and means for adjusting the position of said spring seat on said rod.

16. Valve apparatus as defined in claim 11, wherein said body includes a tubular body section below said lower wall, and said helical support comprises a member disposed in said tubular body section.

17. In well production apparatus for a well producing gas and liquid and having a tubing string extending into the well for conducting liquid from the well: a valve body having means for connecting the same to the tubing string, said body having passages leading between the well outside of said tubing to said tubing, valve means between said passages including a valve member movable between a position at which said valve means is open and a position at which said valve means is closed, and means for operating said valve means, the improvement wherein said means for operating said valve means includes means for normally biasing said valve member to one of said positions, fluid pressure responsive means for moving said member to the other position, said fluid pressure responsive means including a stationary helical member, a shiftable helical member, a resilient helical bladder interposed between said helical members, and means for admitting fluid to said bladder to move said helical members relative to each other to bias said valve member to said other position when the effective fluid pressure internally of said bladder produces a force which exceeds the sum of the forces exerted by said means for biasing said valve member to said one position and the force produced by pressure of fluid externally of said bladder.

18. Well production apparatus as defined in claim 17, wherein said means normally biasing said valve member to one of said positions includes means for adjusting the biasing force thereof to vary the differential pressure responsiveness of said bladder.

19. Well production apparatus as defined in claim 17, wherein said means for admitting fluid to said bladder includes means providing a passage communicating with the well bore above said bladder, the bladder being exposed externally of the fluid in the well bore below said last-mentioned passage.

References Cited UNITED STATES PATENTS 2,248,950 7/1941 Boynton 1O3232 3,363,581 l/1968 Kelley et a1. 103232 3,433,174- 3/1969 Chenoweth 103232 HENRY F. RADUAZON, Primary Examiner US. Cl. X.R. 137-155 

